Ideal CPU and MB temps?

[DHC81]

What is an ideal cpu and mb temp?
I have an asus p4-b, PIV 1.6Ghz, 512MB
Thank you

 

[Deadlifter]

Ambient!

But, with laws of physics/thermodynamics in our way, a good rule of thumb would be case temp 5C over ambient and core temp another 5-8C over case temp. With overclocking the core temps seem to rise pretty quick so you need to ensure you have a really good HSF or water cooling or peltier cooling. A core temp of higher than 20C above ambient is probably as high as you want to go.